Detection of damper motor mechanically disconnected from damper assembly

Patent metadata

Field	Value
Publication number	US-9335063-B2
Application number	US-201414162270-A
Country	US
Kind code	B2
Filing date	Jan 23, 2014
Priority date	Jan 23, 2014
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

In an embodiment, a method of testing a HVAC unit for a disconnected damper motor is provided. An outside air section of a damper assembly is closed and air is circulated through the unit. If a discharge air temperature is not substantially equal to a return air temperature, the damper motor is determined to be disconnected. Otherwise, an economizing function having a free cooling target temperature is started. An outside air temperature is compared to the free cooling target temperature. If the outside air temperature is less than the free cooling target temperature, the damper motor is determined to be disconnected if the damper motor has been commanded to fully open the outside air section. If the outside air temperature is not less than the free cooling target temperature, the damper motor is determined to be disconnected if a discharge air temperature is not substantially equal to an outside air temperature.

First claim

We claim:

1. A method of testing a HVAC unit for a disconnected damper motor, the method comprising:
closing an outside air section of the damper assembly of a HVAC unit;

circulating air through the HVAC unit;
comparing a discharge air temperature to a return air temperature;
if the discharge air temperature is not substantially equal to the return air temperature, determining the damper motor is disconnected from the damper assembly; and
if the discharge air temperature is substantially equal to the return air temperature:
starting an economizing function of a controller of the HVAC unit, the economizing function comprising a free cooling target temperature; comparing a first comparison outside air temperature to the free cooling target temperature;
if the outside air temperature is less than the free cooling target temperature:
determining the damper motor is disconnected from the damper assembly if the damper motor has been commanded to fully open the outside air section; and

if the outside air temperature is not less than the free cooling target temperature,
determining the damper motor is disconnected from the damper assembly if a second discharge air temperature is not substantially equal to a second comparison outside air temperature.

2. The method of claim 1 , wherein the economizing function comprises adjusting the damper assembly to make the temperature of air discharged from the HVAC unit equal to the free cooling target temperature.

3. The method of claim 1 , wherein the first comparison outside air temperature is reused as the second comparison outside air temperature.

4. The method of claim 1 , wherein the first comparison outside air temperature is not reused as the second comparison outside air temperature.

5. The method of claim 1 , further comprising, in response to determining the damper motor is disconnected from the damper assembly, generating an indication the damper motor is disconnected.

6. The method of claim 1 , further comprising, after circulating air through the HVAC unit, waiting for a stabilization period.

7. The method of claim 1 , further comprising, after starting the economizing function, waiting for a stabilization period.

8. The method of claim 1 , further comprising determining, from a motor feedback signal, if the damper motor has been commanded to fully open the outside air section.

9. A HVAC unit controller for testing a HVAC unit for a disconnected damper motor, the unit controller configured to:
close an outside air section of a damper assembly of the HVAC unit;

circulate air through the HVAC unit;
compare a discharge air temperature to a return air temperature;
if the discharge air temperature is not substantially equal to the return air temperature, determine the damper motor is disconnected from the damper assembly; and
if the discharge air temperature is substantially equal to the return air temperature: start an economizing function of the controller, the economizing function comprising a free cooling target temperature;
compare a first comparison outside air temperature to the free cooling target temperature;
if the outside air temperature is less than the free cooling target temperature:
determine the damper motor is disconnected from the damper assembly if the damper motor has been commanded to fully open the outside air section; and

if the outside air temperature is not less than the free cooling target temperature,
determine the damper motor is disconnected from the damper assembly if a second discharge air temperature is not substantially equal to a second comparison outside air temperature.

10. The HVAC unit controller of claim 9 , wherein the economizing function comprises adjusting the damper assembly to make the temperature of air discharged from the HVAC unit equal to the free cooling target temperature.

11. The HVAC unit controller of claim 9 , further configured to reuse the first comparison outside air temperature as the second comparison outside air temperature.

12. The HVAC unit controller of claim 9 , further configured to not reuse the first comparison outside air temperature as the second comparison outside air temperature.

13. The HVAC unit controller of claim 9 , further configured to, in response to determining the damper motor is disconnected from the damper assembly, generate an indication the damper motor is disconnected.

14. The HVAC unit controller of claim 9 , further configured to, after circulating air through the HVAC unit, wait for a stabilization period.

15. The HVAC unit controller of claim 9 , further configured to, after starting the economizing function, wait for a stabilization period.

16. The HVAC unit controller of claim 9 , further configured to determine, from a motor feedback signal, if the damper motor has been commanded to fully open the outside air section.

Assignees

• Lennox Ind Inc

Inventors

• Thomas Herman Marcus
• Troxell Marcus W
• Walter Stephen A

Classifications

• F24F2011/0006

  using low temperature external supply air to assist cooling · CPC title

• F24F11/30 Primary

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F13/10

  movable, e.g. dampers · CPC title

• F24F2221/32

  preventing human errors during the installation, use or maintenance, e.g. goofy proof · CPC title

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title